Ophthalmic solutions typically consist of types that are used multiple times over a fixed period of time after opening (multi-dose type ophthalmic solutions) and types that are used only once (unit-dose type ophthalmic solutions). In particular, multi-dose type ophthalmic solutions typically comprise preservatives to prevent decomposition of the product due to microbial contamination during use and ensure preservation stability.
Benzalkonium chloride (to also be referred to as BAK) is commonly used as a preservative that has superior preservative effects. On the other hand, the use of BAK at a high concentration is known to have the potential to cause corneal disorders. In addition, if a user applies an ophthalmic solution comprising BAK while wearing soft contact lenses, BAK has been indicated to have a detrimental effect on the soft contact lenses such as by causing deformation thereof as a result of making contact therewith. Consequently, the application of an ophthalmic solution comprising BAK is normally prohibited when wearing soft contact lenses.
Diquafosol is a purine receptor agonist, also referred to as P1,P4-di(uridine-5′)tetraphosphate or Up4U, that is used for the treatment of dry eye in Japan in the form of an ophthalmic solution comprising diquafosol sodium at a concentration of 3% (w/v) (trade name: Diquas® Ophthalmic Solution 3%). This Diquas® Ophthalmic Solution 3% comprises BAK for the reason indicated above.
In addition, Patent Document 1 discloses an aqueous ophthalmic solution comprising diquafosol or a salt thereof at a concentration of 0.1% to 10% (w/v) and a chelating agent at a concentration of 0.0001% to 1% (w/v).